Wet methods such as polymerization methods (e.g., a suspension polymerization method, an emulsion polymerization aggregation method, a dispersion polymerization method) and a solution suspension method have been used to produce a toner containing colored resin particles that contain a binder resin and a colorant, since it is easy to control the form, particle diameter and particle distribution of the particles.
However, in the toner production by these methods, there is the following problem: since the toner production includes many steps of adding powdery raw materials (e.g., a colorant and a charge control agent) to liquid raw materials (e.g., a polymerizable monomer and an organic solvent), these powdery raw materials are wet and deposits (hereinafter may be referred to as “scale”) are likely to attach to and accumulate on the inner wall of a pipe or container, resulting in a decrease in yield, a decrease in image quality (since the deposits are detached as coarse particles and mixed into a toner thus obtained) and pipe clogging during continuous production in batches; therefore, the pipe needs to be detached and cleaned.
To solve the problem, various studies have been made from the viewpoint of preventing scale formation, preventing scale attachment to a pipe, etc.
For example, Patent Literature 1 discloses a toner production method in which, in the polymerization step of the toner production by a suspension polymerization method, a carrier gas at a temperature in a given range, is introduced into a gas phase part in a polymerization container containing a polymerizable monomer, thereby preventing the formation and attachment of polymer deposits to the inner wall of the polymerization container.
Patent Literature 1: Japanese Patent Application Laid-Open (JP-A) No. 2011-70048
However, in the method of Patent Literature 1, when the temperature of the polymerization container is high, the polymerizable monomer is vaporized to produce large amounts of vapor, and the amount of vapor that enters a powdery raw material injection pipe, increases to wet the powdery raw materials; therefore, pipe clogging may occur. As just described, the technique to stably and efficiently produce a toner with preventing scale formation, scale attachment to a pipe, etc., is still insufficient and requires further improvement.